For mutual sealing of pressurized and underpressure spaces of a turbine and for sealing them against atmospheric pressure numerous different types of rotor seals are currently used, as well as methods of their arrangement. In order to avoid mechanic damage of the turbine due to increasing vibrations when the turbine passes the critical speed of the rotor, for example during the start-up of the rotor—seals are always designed with the minimum posssible gap between the rotor and the stator—above all movable (retractable) rotor seals are used, whereby during the turbine start-up the movable (retractable) seals are distanced from the rotor and approach it only after passing the critical speed or after achieving operating speed of the turbine, while their movement is allowed by the fact that they are divided into several circumferential segments (generally from 4 to 8), wherein the movement of each of these segments is usually evoked either by a spring—see for example U.S. Pat. No. 7,229,246, or by pressure of sealed medium—see for example US 2003094762. The advantage of the latter is that these mechanisms are, as a rule, simple without a need of outside control or special maintenance. However, their disadavantage is the fact that the pressure of the sealed medium does not always create force necessary to overcome the force of retractring springs, weight of the rotor seal itself and friction forces in the duct, and thus to press the rotor seal to the operating position. This is caused mainly by the fact that the friction forces, which are relatively hard to predict, can moreover change in course of time, for instance as a result of sedimentation of impurities, and can even completely block the movement of the rotor seal. In pursuit of solving these negative effects, the construction of rotor seals generally becomes very demanding as to the mounting—see for example EP 2048366, where the rotor seal has large dimensions, while the width of its head exceeds the widthof its sealing comb, which complicates or totally disables utilization of several such rotor seals arranged in a row next to each other.
The goal of the invention is to propose construction and arrangement of a segmented retractable rotor seal, which would at least partially eliminate the drawbacks of the background art—would ensure reliable pressing of the rotor seal towards the rotor and at the same time enable to arrange required number of rotor seals next to each other.